28 NEW YORK STATE MUSEUM 



broic facies on the one hand, and a white, ahnost purely feld- 

 spathic facies on the other. 



The syenite-granite series exhibits tlie usual variations from a 

 typical, greenish gray, moderately quart?:ose syenite to both t[uartz- 

 less dioritic or gabbroic facies and granitic, very quartzose facies. 

 Tongues of syenite and granite were found clearly cutting the 

 anorthosite at several localities. There are many occurrences of a 

 peculiar syenitic looking rock with large bluish gray labradorite 

 crystals and this is almost certainly a rock intermediate between 

 anorthosite and syenite, having been produced by assimilation of 

 anorthosite around the borders of the molten syenite. 



Bodies of gabbro are not common, one considerable stock having 

 been found on Pulpit mountain, while another large mass enters 

 the quadrangle from one to two miles southeast of Upper Jay. 



Diabase dikes of small size ari^ numerous, being especially 

 abundant from Keene Center northward for several miles. 



Zones of excessive jointing, accompanied by more or less fault- 

 ing, are prominently developed through the Wilmington notch and 

 in the valley from Keene Center northward. 



Perhaps the most remarkable topographic feature of the cjuad- 

 rangle is the Wilmington notch which is certainly of postglacial 

 origin, the waters first having started over a preglacial divide there 

 as the outlet of a large lake which occupied the broad lowland area 

 south and southeast of Lake Placid village. 



The very interesting glacial lakes of the quadrangle are being 

 studied by Mr H. L. Ailing. 



The survey of the Ausable and Mount Marcy quadrangles, which 

 has been in charge of Prof. J. F. Kemp, is well toward completion, 

 but the final touches to the work have been temporarily suspended. 



Landslides in the Hudson valley. The clays of the Hudson 

 valley have long been the seat of soil displacements of greater or 

 less moment, and during the past season one occurred on the prop- 

 erty of the Knickerbocker Portland Cement Co. near Hudson, 

 which was attended with very serious results. It was made the 

 occasion for a careful investigation by Mr D. H. Newland, in which 

 he was aided in every way by the company. The condition govern- 

 ing these displacements and the important results of this investi- 

 gation are given in the appendix to this report. 



Underground waters. Requests for information in regard to 

 underground water supplies increase every year. These inquiries 

 can be answered only tentatively and with great reserve, for 

 knowledge of the underground waters of New York is very largely 



